Sudden fever: what to know

Fever is a rise in body temperature that can happen when the immune system responds to infection. A common cold, COVID-19, acute bronchitis or another respiratory illness may bring cough, sore throat or congestion. Skin redness and tenderness can occur with cellulitis; a widespread itchy rash may occur with chickenpox. Bronchiolitis and croup mainly affect young children and can cause breathing symptoms. Less common infections, including brucellosis, may need specific medical assessment. Fever by itself does not reveal which infection is present.

Record when it began and look for breathing difficulty, rash, pain, vomiting, diarrhoea, confusion or reduced drinking. Consider recent travel, sick contacts, new medicines and heat exposure when describing the illness.

Rest, drink fluids regularly and wear light, comfortable clothing. A lukewarm wash may feel soothing; avoid extreme cooling that causes shivering. If you use a fever medicine, follow the package directions and check with a pharmacist if you are pregnant, treating a child, or taking other medicines. Do not give aspirin to children. Stay home from close contact while unwell and wash your hands. Arrange medical advice if fever persists, returns after improving or is difficult to manage.

Seek emergency help for trouble breathing, blue or grey lips, a seizure, severe dehydration, confusion, unusual sleepiness, a stiff neck, severe headache, or a rapidly spreading rash. A young baby with fever needs prompt professional assessment. Seek same-day advice for persistent vomiting, severe pain, a weakened immune system or fever after significant travel. In children, changes in alertness, drinking or urination matter as much as the temperature reading.

Ask what may be causing the fever, whether an examination or test is needed, which medicine and dose are suitable, and how long to monitor symptoms. Share the temperature method, start time, associated symptoms, recent travel, medical conditions and medicines.